A national census was conducted in 1999, but its final results were never released. A new census was undertaken in 2009, but it turned out to be controversial, as the questions about ethnic affiliation seemed inappropriate after the ethnic violence of the previous year.[1] Preliminary results of the census were published in 2010.[2]

Kenya's population was reported as 38.6 million in 2009, compared to in 28.7 million in 1999, 21.4 million in 1989 and 15.3 million 1979,[3] an increase by a factor of 2.5 over 30 years, or an average growth of more than 3% per year. The population growth rate has been reported as somewhat reduced during the 2000s and is now estimated at 2.7% (as of 2010), resulting in an estimate of a total population 41 million in 2011.

Kenya has a very diverse population that includes most major ethnic, racial and linguistic groups found in Africa. The majority of the country's population belongs to various Bantu sub-groups, with a significant number of Nilotes.

Cushitic peoples form a small ethnic minority of about 2%, mostly represented by Oromo and Somali speakers.

Swahili and English are official languages. Swahili is compulsory in primary education, and, along with English, serves as the main lingua franca between the various ethnic groups.

Kenya's diversity is such that its largest ethnic group, the Kikuyu, make up for less than a fifth of total population. Ever since Kenyan independence in 1963, Kenyan politics have been characterized by ethnic tensions and rivalry between the larger groups, devolving into ethnic violence in the 2007–2008 Kenyan crisis.

Nilotes are the second-largest group of peoples in Kenya. They speak Nilo-Saharan languages and came to Southeast Africa by way of South Sudan.[6] Most Nilotes in Kenya are herdsmen, and they have a fearsome reputation as warriors and cattle-rustlers. The most prominent of these groups include the Luo, Maasai, the Samburu, the Turkana, and the Kalenjin.[6] As with the Bantu, the Nilotes have adopted many customs and practices from the Cushitic groups, including the age set system of social organization, circumcision, and vocabulary terms.[8][9]

The Cushitic-speaking peoples are divided into two groups: the Southern Cushites and Eastern Cushites.

The Southern Cushites were the second earliest inhabitants of Kenya after the indigenous hunter-gatherer groups,[11] and the first of the Cushitic-speaking peoples to migrate from their homeland in the Horn of Africa about 2000 years ago.[9] Responsible for having introduced irrigation and composting techniques to Southeast Africa,[12] they were progressively displaced in a southerly direction and/or absorbed by the incoming Nilotic and Bantu groups until they wound up in Tanzania.[9] As a consequence of these movements, there are no longer any Southern Cushites left in Kenya (the Dahalo originally being pre-Cushitic peoples who adopted the language of their dominant Southern Cushitic neighbors sometime toward the last millennium BCE[12]).

The Eastern Cushites include the Oromo and the Somali. Of these, the Somali are the most recent arrivals to Kenya, having first come from Somalia only a few centuries ago.[9] After the Northern Frontier District (North Eastern Province) was handed over to Kenyan nationalists at the end of British colonial rule in Kenya, Somalis in the region fought the Shifta War against Kenyan troops to join their kin in the Somali Republic to the north. Although the war ended into a cease-fire, Somalis in the region still identify and maintain close ties with their kin in Somalia, and see themselves as one people.[13] An entrepreneurial community, they established themselves in the business sector, particularly in Eastleigh.[14]

Arabs form a small but historically important minority ethnic group in Kenya. They are principally concentrated along the coast in cities such as Mombasa. A Muslim community, they primarily came from Oman and are engaged in trade. Arabs are locally referred to as Washihiri or, less commonly, as simply Shihiri in the Bantu Swahili language, Kenya's lingua franca.[10] According to the 2009 Census, Kenyan Arabs number 40,760 people.[15]

Indians are primarily descendants of migrants who arrived in Kenya between 1896 and 1901, when some 32,000 indentured labourers were recruited from British India to build the Kenya-Uganda Railway.[16] Since Kenyan independence, they have been principally concentrated in the business sector. Many Kenyan Indians hail from the Gujarat region. While there have been some race-related tensions with the local Bantu and Nilotic majority, Indians now form one of the more prosperous communities in the region.[10] According to the 2009 Census, Kenyan Asians number 46,782 people, while Asians without Kenyan citizenship number 35,009 individuals.[15]

Europeans in Kenya primarily consist of descendants of British colonials. Many are of aristocratic descent and still continue to wield significant influence, especially over Kenya's political elite. Since the Independence of Kenya, Britons and other Europeans in Kenya also continue to dominate the local business community.[10] According to the 2009 Census, Kenyan Europeans number 5,166 people, while Europeans without Kenyan citizenship number 27,172 individuals.[15]

Kenya's various ethnic groups typically speak their mother tongues within their own communities. The two official languages, English and Swahili, are used in varying degrees of fluency for communication with other populations. English is widely spoken in commerce, schooling and government.[17] Peri-urban and rural dwellers are less multilingual, with many in rural areas speaking only their native languages.[18]

According to Ethnologue, there are a total of 69 languages spoken in Kenya. Most belong to two broad language families: Niger-Congo (Bantu branch) and Nilo-Saharan (Nilotic branch), spoken by the country's Bantu and Nilotic populations, respectively. The Cushitic and Arab ethnic minorities speak languages belonging to the separate Afro-Asiatic family, with the Indian and European residents speaking languages from the Indo-European family.[19]

According to the 2010 revison of the World Population Prospects, the total population was 40,513,000 in 2010 compared to only 6,077,000 in 1950. The proportion of children below the age of 15 in 2010 was 42.5%, 54.9% was between 15 and 65 years of age, and 2.7% was 65 years or older.[20]

Like the demographics of Africa in general, Kenya is plagued by high infant mortality, low life expectancy, malnourishment (32%of population) and HIV/AIDS. While these concerns remain grave, a trend towards improvement is reported in the period of 2006 to 2010: Infant mortality was at estimated at 59.26 deaths/1,000 live births as of 2006, decreasing to 54.7 deaths/1,000 live births as of 2010. Life expectancy was estimated at 48.9 years as of 2006, and has risen to 64 years in 2012.[23]

According to 2008-09 Kenyan government survey, total fertility was 4.6 with contraception usage rate among married women was 46 percent.[24] Total fertility rate has decreased slightly, from 4.91 children born per woman (2006 estimate), to a value of 4.38 (2010 estimate). Literacy (age 7 and over can read and write) was estimated at 85.1% in 2003 (male: 90.6%, female: 79.7%).